Royal College of Obstetricians and Gynaecologists (RCOG). Birth after previous caesarean birth. London (UK): Royal College of Obstetricians and Gynaecologists (RCOG); 2007 Feb. 17 p. (Green-top guideline; no. 45). [116 references]

A direct comparison of recommendations presented in the above guidelines for the management of vaginal birth after cesarean (VBAC) is provided below.

Areas of Agreement

Candidates for VBAC

The American College of Obstetricians and Gynecologists (ACOG) and the Royal College of Obstetricians and Gynaecologists (RCOG) agree that that most women with a history of one or two uncomplicated low transverse caesarean sections, in an otherwise uncomplicated pregnancy at term and with no contraindications to vaginal birth, are candidates for and should be counseled about VBAC.

There is further agreement that women at high risk for complications—including those with a history of one classical or T-incision, or prior uterine rupture—are not generally candidates for VBAC. RCOG also cites a history of three or more previous caesarean deliveries as a contraindication to VBAC. ACOG notes that data regarding the risk for women undergoing TOLAC with more than two previous cesarean deliveries is limited. With regard to prior low-vertical incisions, ACOG states that recognizing the limitations of available data, health care providers and patients may choose to proceed with TOLAC in the presence of a documented prior low vertical uterine incision. RCOG cites prior inverted T- or J-incisions and prior low vertical incisions as variants associated with an increased risk of uterine rupture.

ACOG and RCOG provide recommendations for VBAC in special circumstances. Concerning twin gestation, ACOG concluded that women with one previous cesarean delivery with a low transverse incision, who are otherwise appropriate candidates for twin vaginal delivery, may be considered candidates for TOLAC. With regard to macrosomia, ACOG states that it is appropriate for health care providers and patients to consider past and predicted birth weights when making decisions regarding TOLAC, but suspected macrosomia alone should not preclude the possibility of TOLAC. RCOG does not make specific recommendations, noting that study sample sizes are underpowered to provide reliable evidence suitable for any clinical practice recommendation in relation to twin gestation, fetal macrosomia and short interdelivery interval. They advise that a cautious approach be used when considering planned VBAC in women with these circumstances, as there is uncertainty in the safety and efficacy of planned VBAC in such situations. Both groups also address other special circumstances. ACOG discusses gestation beyond 40 weeks, breech presentation, unknown type of uterine decision, second trimester delivery/delivery of an intrauterine fetal demise; RCOG discusses preterm birth.

Induction and Augmentation of Labor

ACOG and RCOG agree that induction of labor for maternal or fetal indications is an option for women undergoing a TOLAC. There is further agreement that when informing a woman about induction (prostaglandin or non-prostaglandin methods) and/or augmentation, clear information should be provided on all potential risks and benefits, especially the potential increased risk of uterine rupture and the potential decreased possibility of achieving VBAC. RCOG specifies that the decision to induce, the method chosen, the decision to augment with oxytocin, the time intervals for serial vaginal examination and the selected parameters of progress that would necessitate and advise on discontinuing VBAC should be discussed with the woman by a consultant obstetrician.

Both ACOG and RCOG address the use of prostaglandins for induction of labor, with ACOG recommending against the use of misoprostol (PGE1) for third trimester cervical ripening or labor induction in patients who have had a cesarean delivery or major uterine surgery. With regard to dinoprostone (PGE2), ACOG states that it is difficult to make definitive recommendations regarding its use, and cites one large study that found an increase in uterine rupture only when oxytocin was used after cervical ripening with prostaglandins. Therefore, ACOG continues, selecting women most likely to give birth vaginally while avoiding sequential use of prostaglandins and oxytocin appears to have the lowest risks of uterine rupture. RCOG does not differentiate between PGE1 and PGE2, but recommends women be informed of the higher risk of uterine rupture with induction of labor with prostaglandins. Given the risks and the absence of direct robust evidence, RCOG continues, it is important not to exceed the safe recommended limit for prostaglandin priming in women with prior caesarean birth. Due consideration should be given to restricting the dose and adopting a lower threshold of total prostaglandin dose exposure.

With regard to augmentation using oxytocin, ACOG concludes that available studies support its use in patients undergoing TOLAC. RCOG states that the additional risks in augmented VBAC mean that: although augmentation is not contraindicated it should only be preceded by careful obstetric assessment, maternal counseling, and by a consultant-led decision; and that oxytocin augmentation should be titrated such that it should not exceed the maximum rate of contractions of four in 10 minutes; the ideal contraction frequency would be three to four in 10 minutes. RCOG also recommends careful serial cervical assessments be performed for both augmented and non-augmented labors to ensure adequate cervicometric progress.

ACOG addresses mechanical cervical ripening and induction with a transcervical catheter, and concludes that given the lack of compelling data suggesting increased risk, such interventions may be an option for TOLAC candidates with an unfavorable cervix.

Antenatal Counseling

Both groups agree that women with a prior caesarean birth should be counseled regarding potential maternal and perinatal risks (most notably uterine rupture), as well as benefits of both VBAC and ERCS. There is also agreement that the discussion should be tailored to the patient's individual circumstances so that she can choose her intended mode of birth based on personally relevant information. RCOG specifies that individual characteristics that should be discussed include: her personal motivation and preferences to achieve VBAC or ERCS; her attitudes towards the risk of rare but serious adverse outcomes; her plans for future pregnancies; and her chance of a successful VBAC (principally whether she has previously had a vaginal birth). ACOG notes that it is preferable to discuss VBAC early in a woman's prenatal care course, and that antenatal counseling should be adapted to any circumstances that may change the risks or benefits of TOLAC as the pregnancy progresses. ACOG also recommends that counseling consider the resources available to support women electing TOLAC at their intended delivery site, and whether such resources match those recommended for caring for women electing TOLAC. RCOG and ACOG agree that reasonable attempts should be made to review the operative notes of the previous cesarean (especially if the type of previous uterine incision is in doubt).

RCOG recommends that women be informed that planned VBAC carries: a 22-74/10,000 risk of uterine rupture (compared to virtually no risk of rupture in ERCS); a 1% additional risk of either blood transfusion or endometritis compared with ERCS; an 8/10,000 risk of the infant developing HIE; and a 2-3/10,000 additional risk of birth-related perinatal death when compared with ERCS (comparable to the risk for women having their first birth). One advantage of VBAC compared to ERCD addressed by both groups is the avoidance of potential future maternal consequences of multiple cesarean deliveries. An additional benefit cited by ACOG is the avoidance of major abdominal surgery, resulting in lower rates of hemorrhage, infection, and a shorter recovery period. Additionally, RCOG notes that attempting VBAC probably reduces the risk that the baby will have respiratory problems after birth: rates are 2-3% with planned VBAC and 3-4% with ERCS.

RCOG recommends that women be informed that, overall, the chances of successful planned VBAC are 72-76%. ACOG states that most published series of women attempting TOLAC have demonstrated a probability of VBAC of 60-80%. The groups agree that the probability that a woman attempting TOLAC will achieve VBAC depends on her individual combination of factors. There is agreement that factors associated with unsuccessful VBAC include: induced labor, no prior vaginal birth, advanced gestational age (≥40 weeks), advanced maternal age, high maternal BMI, high birth weight, previous cesarean section for a recurring indication, and non-white ethnicity.

Both groups address scoring systems that have been developed to predict the likelihood of VBAC success or uterine rupture in planned VBAC. RCOG notes that their usefulness in assisting women to make the decision about whether VBAC or ERCS is the best choice in their personal situation remains to be determined. ACOG states that while most of the scoring models have had limited success, one model was developed specifically for women undergoing TOLAC at term with one prior low transverse cesarean delivery incision, singleton pregnancy, and cephalic fetal presentation, and it may have utility for patient education and counseling for those considering TOLAC at term.

Intrapartum Management

ACOG and RCOG agree that planned VBAC should be undertaken in a suitably staffed and equipped delivery suite at a facility capable of providing emergency care (most notably emergency cesarean section deliveries), with obstetric, anesthetic, operating room, and neonatal/pediatric/midwifery staff support continuously available. When resources for immediate cesarean delivery are not available, ACOG recommends that health care providers and patients discuss the hospital's resources and availability of necessary staffs, and carefully consider the decision to offer and pursue TOLAC in a setting in which the option of immediate cesarean delivery is more limited. If the appropriate resources are not available, potential alternatives to consider early in the course of antenatal care cited by ACOG include: referral of patients to a facility with available resources and the creation of regional centers where patients interested in TOLAC can be readily referred and needed resources can be more efficiently and economically mobilized. ACOG notes, however, that in areas with fewer deliveries and greater distances between delivery sites, organizing transfers or accessing referral centers may be untenable. ACOG adds that respect for patient autonomy supports the concept that patients should be allowed to accept increased levels of risk; however, patients should be clearly informed of such potential increase in risk and management alternatives. They emphasize that none of the principles, options, or processes outlined in the guideline should be used by centers, health care providers, or insurers to avoid appropriate efforts to provide the recommended resources to make TOLAC as safe as possible for those who choose this option.

Both groups recommend continuous electronic fetal monitoring and intrapartum care for the duration of planned VBAC to enable prompt identification and management of uterine scar rupture. According to ACOG, uterine rupture is often sudden and may be catastrophic, and accurate antenatal predictors of uterine rupture do not exist. RCOG similarly notes that there is no single pathognomic clinical feature that is indicative of uterine rupture. Both groups agree, however, that signs/symptoms of uterine rupture to be vigilant for include: fetal and/or maternal heart rate abnormality; loss of fetal station of the presenting part; excessive vaginal bleeding or hematuria; and new onset of uterine scar pain/tenderness. ACOG also cites increased uterine contractions; RCOG also cites severe abdominal pain, chest pain or shoulder tip pain, and cessation of previously efficient uterine activity.

There is further agreement that epidural analgesia may be used in planned VBAC. ACOG notes that adequate pain relief may encourage more women to choose TOLAC. They add that effective regional analgesia should not be expected to mask signs and symptoms of uterine rupture, particularly because the most common sign of rupture is fetal heart tracing abnormalities.

With regard to intrauterine pressure catheters, RCOG notes that their routine use in the early detection of uterine scar rupture is not recommended. ACOG similarly states that no data suggest that intrauterine pressure catheters are superior to external forms of monitoring, and there is evidence that their use does not assist in the diagnosis of uterine rupture.